WEB Ab-initio multiscale simulation of ionization and charge transport in doped organic semiconductorsThursday (24.09.2020) 10:10 - 10:25 M: Modelling and Simulation 1 Part of:
Doped organic materials allow reducing the power consumption and efficiency of organic photovoltaic and light-emitting devices. In recent years, theoretical description of doping processes in organic materials has evolved from relying on models inherited from doped inorganic materials to using comprehensive models based on ab initio methods. However, existing approaches lack the essential feature to explicitly link the chemical structure along with related properties of the constituting molecules to charge dynamics in doped materials.
Here, we present a theoretical approach that consists of three steps: (1) generation of the doped material morphology (DEPOSIT method [J. Comput. Chem. 2013, 34, 2716-2725]); (2) extraction of quantum mechanical properties of molecules in their unique polarizable environment on the DFT level (Quantum Patch method [J. Chem. Theory Comput. 2014, 10, 9, 3720-3725]) and (3) simulation of charge carrier dynamics using kinetic Monte-Carlo method [Nat. Commun. 2019, 10, 4547; PCCP. 2020, 22, 10256-10264 ].
Using this method, we have analyzed charge carrier dynamics in several prototypical amorphous organic materials including TPD, alpha-NPD and SpiroTAD doped with F4TCNQ. We have extracted conductivity, density of states, thermal activation energy and the fraction of mobile charge carriers and assessed good agreement with existing experimental data. Our studies deliver microscopic insight on the doping process in organic semiconductors and we hereby illustrate how the used method can be applied for virtual molecular design of host-dopant combinations to increase performance e.g. in OLED or OPV devices.